INTERACTIONS OF FOLIAR INSECTICIDES APPLIED WITH PYRITHIOBAC

Field and greenhouse experiments were conducted to determine the effec t of selected insecticides on cotton when applied in combination with pyrithiobac. In the field, acephate, azinphos-methyl, bifenthrin, chlo rpyrifos, dicrotophos, esfenvalerate, malathion, methomyl, or oxamyl w as applied foliarly with the sodium salt of pyrithiobac at 70 g ae/ha. Pyrithiobac plus malathion resulted in greatest injury when compared with other treatments. There were no differences observed in fruiting characteristics of cotton. Cotton yield was lower with oxamyl, methomy l, and chlorpyrifos when applied in combination with pyrithiobac in on e of three experiments. In greenhouse experiments, injury due to pyrit hiobac was greater in a cool (21 C day, 13 C night) temperature than i n a warm temperature (30 C day, 21 C night), but differences were less than 15%. Pyrithiobac plus malathion in the cool environment injured cotton more severely 7 DAT than either pesticide alone. Adding insecti cides to pyrithiobac did not influence injury in the warm environment.